What is the site  hierarchy? If you have one top-level site, and you want to display a list of sub-sites that the user  can access, I can provide you with some code that will do that.

If, on the other hand, you have many sites  that are all top-level sites, that I cannot help you with, although I’m sure there is a way to do it as well.

We have one top level site  and then all sites  are under sites so it would be

http://parent site for example

and then all other sites would be

http://parentsite/sites/A
a sub site would be http://parentsite/sites/A/AA and so on and so forth

http://parentsite/sites/B
http://parentsite/sites/C

Poke around and see if you can’t find  a web part to do this. I didn’t see one in my list of stuff, but it is well worth the Google time to look for a canned solution to do this.